For Impreza WRX/STi EJ20 EJ25 TD05H 18G Turbocharger with Internal Wastegate Turbine A/R .49 High Quality Material, Cast Housing with Durable Steel; Boost Engine Horsepower Significantly Increase Engine Power and Torque Outpout; Maintain Combustion Chamber Pressure and Fuel/Air Load Contructed with High Quality Material; Built for Durability and Strength; Internal Wastegate Setting: 12 psi Capable of Boosting Horsepower up to 380+ BHP / Exhaust (Turbo Manifold) Flange: Standard Subaru 3-Bolt / Exhaust (Downpipe) Flange: Standard TD05 18G 5-Bolt Inlet/Outlet: 2.375"/2" / Compressor Inducer: 50.3mm / Turbine Exducer: 49.2mm / Turbine A/R: .49